The man accused of strangling his girlfriend and posting pictures of her dead body on 4Chan, went drinking in a bar just hours after the killing.

David Kalac is accused of brutally murdering Amber Lynn Coplin in her home in Port Orchard, Washington, before going on the run and leaving her 13-year-old son to discover the body when he came home from school.

The 33-year-old walked into a Portland bar and spent hours chatting to customers and drinking beer and vodka before handing himself over to police in Wilsonville, Oregon, last Wednesday.

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Killer: David Kalac, 33, pictured after his arraignment, visited a bar in Portland and spent hours drinking beer and vodka, shortly after allegedly strangling his girlfriend and posting pictures of her dead body online

Ryan Stowe, owner of The Know bar in Portland, said Kalac drank three cans of Pabst Blue Ribbon and a Vodka with Red Bull.

Kalac spent at least four hours drinking in the bar, 'chatting with customers and spilling a beer before leaving a generous tip,' NY Daily News reports.

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'It’s weird that he was just hanging out here, knowing police were looking everywhere for him,' Mr Stowe said.

'He wasn’t worried about anyone seeing him or anything.'

Following an alleged handwritten confession from Kalac prosecutors have increase the charges from second-degree murder to first-degree murder.

Murdered: A coroner's report has found that the injuries on Amber Coplin's body is consistent with manual strangulation, and Kalac has confessed to the killing

Arrest: Kalac, 33, pictured after he handed himself over to police shortly after leaving The Know bar in Portland, has been charged with first-degree murder

Horror: The body of Amber Coplin was discovered by her 13-year-old son and her estranged husband

The new charge includes a domestic violence enhancement and an aggravated circumstance of having 'a destructive and foreseeable impact on persons other than the victim,' said Kitsap County sheriff's spokesman Scott Wilson said

Kalac was arraigned on the charges in Kitsap County Superior Court in Port Orchard, west of Seattle, Friday afternoon.

Kalac's lawyer asked to have the plea postponed and his next court date is Friday, November 14, with bail set at $2million.

Earlier in the day, the Kitsap County Sheriff's Office filed a probable cause certificate that detailed the new evidence that supported the tougher charges.

According to the document, when Kalac emerged from the woods near Portland, Oregon, and surrendered Wednesday, Clackamas County deputies found a note admitting to the crime.

It read: 'I killed Amber Coplin. I strangled her with my hands, then a shoelace.

Scene: She was found murdered inside her Port Orchard, Washington home, pictured, on Tuesday afternoon - just half an hour after the killer apparently posted grisly images of her naked body online

Sick: Kalac, her boyfriend, also allegedly left messages scrawled inside her bedroom, including 'she killed me first' on a picture and 'dead' across the driving license, which was found near her head

'I had No reason other than I was Drunk and she pissed me off. Running from the cops was so fun. DK.'

The color of the ink and the writing style were consistent with messages authorities say Kalac left at the crime scene, the sheriff's document said. It also quoted from notes authorities say Kalac posted online with the images of Coplin.

A quote from one site said: 'Check the news for port orchard Washington in a few hours. Her son will be home from school soon.

'He'll find her, then call the cops. I just wanted to share the pics before they find me.'

Another post said that he learned that she was having an affair with another man and that made him angry.

The sheriff's document said the Kitsap County coroner's office had determined the cause of death was 'ligature strangulation with blunt force trauma to the head,' and the forensic pathologist said Kalac's hyoid bone, under the chin, was fractured.

'Based on my training and experience this is consistent with manual strangulation,' Detective Chad Birkenfeld said in the document.